Question

-v28×(v64+v112-5v7)×v7

Answer 1

$28=2^2 cdot 7 -sqrt{28} cdot sqrt{7} = -sqrt{2^2 cdot 7^2} = -14 \ 64=8^2, sqrt{64}=8, 112=2^4 cdot 7, sqrt{112}=4 sqrt{7} \ -sqrt{28}(sqrt{64}+sqrt{112}-5sqrt{7})sqrt{7} =14 cdot (sqrt7 -8)$